1. Field of the Invention
The present invention relates generally to an image-forming apparatus and, more particularly, to an auger and waste toner reservoir for removing and storing residual toner from a photoconductive drum.
2. Description of the Prior Art
Image forming devices including copiers, laser printers, facsimile machines, and the like, include a photoconductive drum (hereinafter referred to as a drum) having a rigid cylindrical surface that is coated along a defined length of its outer surface. The surface of the drum is charged to a uniform electrical potential and then selectively exposed to light in a pattern corresponding to an original image. Those areas of the photoconductive surface exposed to light are discharged thus forming a latent electrostatic image on the photoconductive surface. A developer material, such as toner, having an electrical charge such that the toner is attracted to the photoconductive surface is brought into contact with the drum""s photoconductive surface. A recording sheet, such as a blank sheet of paper, is then brought into contact with the photoconductive surface and the toner thereon is transferred to the recording sheet in the form of the latent electrostatic image. The recording sheet is then heated thereby permanently fusing the toner to it. In preparation for the next image forming cycle, the photoconductive surface may be discharged by an erase lamp and residual toner is removed by a cleaner blade, such as a brush or scraper, that contacts the drum surface. The toner falls into an auger or conveyor that moves the toner away from the drum. A waste toner reservoir is often positioned adjacent to the drum for housing the residual toner.
Preferably, the overall size of the image forming apparatus is as small as possible. The small size allows a user to more easily move the device, and also requires less space on a user""s desk or workstation. Therefore, there is a tradeoff between a large waste toner reservoir that can hold a large amount of residual toner without becoming filled and a smaller reservoir that fits within the image forming device without occupying an excessive amount of space.
Several previous toner removal systems have used fans or other like devices to move the toner away from the drum. Conduits placed along the drums capture and direct the toner to remote areas of the apparatus away from the drum. Fans are placed along the conduits for blowing the toner along the length of the conduit to remote locations where the toner can be removed from the image forming apparatus. These fans add cost to the printer, and a single image forming device often requires more than one fan to adequately move the toner. The fans may also be unreliable, either failing to operate effectively or breaking-down requiring continual maintenance. Breakdowns are especially likely because the fans are constantly exposed to the dry, powdery toner that may clog and foul the fan components. A blocked toner removal system requires the printer to be taken off line and disassembled, which is time consuming and aggravating for a user. Fans additionally add noise to the image-forming process which is undesirable because the devices are often positioned at user""s workstations where a quiet atmosphere is maintained for efficient working conditions.
Other waste toner reservoirs have been positioned to use gravity to move the toner away from the drums. As toner is moved by an auger into the reservoir, it falls into the reservoir filling from the bottom to the top and becomes unusable once the level of toner reaches the toner inlet. These gravity systems reduce the effective design alternatives for the apparatus because the positioning of the reservoir relative to the drum is critical. Positioning the reservoir below the drum to utilize the gravity flow often requires an additional amount of space, thereby resulting in an increased overall size of the image forming apparatus. This problem is compounded in color printing devices that have multiple drums and reservoirs.
Thus, there remains a need for a toner removal system for an image-forming apparatus that provides adequate space for holding residual toner but does not require a large amount of space within the apparatus.
The present invention is directed to a toner removal device for removing residual toner from within an image-forming apparatus. The invention includes a waste toner reservoir aligned along an end of the drum for storing residual toner removed from the drum. An auger extends along the drum and moves the toner into an opening in the waste toner reservoir. The toner is directed into all areas of the waste toner reservoir, both areas above and below the level of the opening providing for sizing and positioning the waste toner reservoir to occupy a minimal amount of room within the interior of the image forming apparatus.
A pumping cylinder may be mounted around the auger adjacent to the waste toner reservoir to further assist in pumping the toner. The pumping cylinder extends around helical blade of the auger such that as the auger rotates, the toner is forced through the pumping cylinder and into the waste toner reservoir. The pumping cylinder assists in preventing the toner from back-flowing from the waste toner reservoir into the areas of the drum. Preferably, the auger extends through the pumping cylinder and into the interior section of the waste toner reservoir to further assist in toner pumping.